1. Field of the Invention
This invention relates to electronic musical tone synthesis and in particular is concerned with implementation of solo tone color changes in response to accompaniment chords.
2. Description of the Prior Art
One of the principal attributes of an electronic musical instrument, such as an organ, is the ease with which tone changes can be made. The use of a plurality of keyboards allows the musician to instantaneously change sounds by playing on the keyboards each of which usually controls a different preselected tone color. The tone color is selected for each keyboard by actuating a set of tone switches, or stops, which are arranged in groups which correspond to each of the keyboard arrays of keyswitches. There is a listener emotional need for changing tone colors to prevent a fatigue effect that is associated with a sameness in the aural response of the listener.
Designers of electronic musical instruments have exploited the mechanical-like tone production implementation of keyboard instruments to provide a variety of ancillary systems to aid the neophyte musician. These ancillary systems have a common objective of enabling the new musician to generate tonal effects which usually can only be performed when one has attained a high degree of dexterity on the keyboard. Such ancillary systems include automatic arpeggios, accompaniment chords controlled in preselected rhythmic patterns, automatic pedal accompaniment played in rhythmic patterns, automatic glissandos, and automatic portamento frequency transitions.
Accomplished keyboard instrument players will augment the solo line of a musical piece by adding notes to an otherwise monophonic solo part. This is usually accomplished by inserting notes on the solo keyboard corresponding to notes belonging to the chords that are played on the accompaniment keyboard. The notes added to the solo part, often referred to as "fill-ins," are usually not scored in the written music. The proper selection of fill-notes requires a musical sophistication on the part of the player which is beyond the limitations of the average beginning musician.
Several systems have been developed which add fill-in notes to a keyboard by transferring notes played on an accompaniment keyboard. Such a system is disclosed in U.S. Pat. No. 3,823,246 entitled "Chord Playing Organ Including A Circuit Arrangement For Adding Fill-In Notes To The Solo Part." The patent describes apparatus which in the fill-in mode of operation utilizes the lower, or accompaniment, keyboard of an organ as a monophonic chord input data set of keys. In this mode a single finger is used to actuate a keyboard switch and thereby select a predetermined chord type. The selected chord is sounded for the set of tone switches actuated for the accompaniment keyboard. Two notes of the automatically generated chord are transferred to the solo keyboard and the transferred notes are sounded at the same time that a note is actuated on the solo keyboard. The transferred notes are translated so that they sound in an octave below the actuated solo note. The two transferred notes are selected from the automatically generated chord by using a selection logic which is responsive to the actuated solo note. In this fashion dissonant harmonic intervals can usually be eliminated. Circuitry is provided to inhibit the chord generating apparatus if more than one note is actuated on the lower keyboard.
An improvement to the system disclosed in U.S. Pat. No. 3,823,246 is contained in U.S. Pat. No. 3,990,339 entitled "Electronic Organ And Method Of Operation." The musical effect produced by the disclosed system is very similar to that previously described for U.S. Pat. No. 3,823,246. A time delay is incorporated into the logic so that fill-in notes are automatically inhibited during the execution of notes played in rapid succession on the solo keyboard.
In U.S. Pat. No. 4,368,658 entitled "Apparatus for Solo Harmony Transfer In An Electronic Musical Instrument" apparatus is disclosed for providing fill-in notes. The fill-in notes are chosen by selecting a member of a library of stored chord types. The selected member is one which is closest to the notes played on the accompaniment keyboard. The closest decision is made by processing the actuated keyswitch data with two sets of matched filters. The chord type decision is made to correspond to a matched filter combination which produces a maximum response. A root note is also chosen for the selected chord type. The selected chord type and the chosen root note are used to provide the fill-in notes.